The Cost-effectiveness of Improving Indoor Air Ventilation for the Prevention of Covid-19 in Commercial Spaces

Abstract Objective: Airborne infection from aerosolized SARS-CoV-2 poses an economic challenge for the large number of small businesses without existing heating, ventilation, and air conditioning (HVAC) systems. Standalone units have been recommended, but are costly and may not achieve adequate air exchange to prevent infection.Study design: Cost-effectiveness analysis with Monte Carlo simulation.Methods: We built a probabilistic decision-analytic model in a Monte Carlo simulation that examines aerosol transmission of SARS-CoV-2 in an indoor space. As a case study, we modeled a poorly ventilated indoor restaurant. We evaluated the cost-effectiveness of improving ventilation rate to 12 air changes per hour (ACH), the equivalent of hospital-grade filtration systems used in emergency departments. Our base-case scenario assumes that the mean year-round prevalence of actively infectious cases in the community surrounding the restaurant is 1%, and that 50% of patrons were fully vaccinated. Our best-case scenario assumes a community prevalence of 0.1% and 70% of patrons vaccinated, and our worst-case scenario assumes a community prevalence of 2% and 0% of patrons vaccinated. We also provide a customizable online tool.Results: All 3 scenarios resulted in a net cost-savings and infections averted. For the base-case scenario, improving ventilation to 12 ACH was associated with 33 (95% Credible Interval [CrI]: 18-50) aerosol infections averted over one year, producing an estimated cost savings of -$97,467 (95% CrI: -$156,760, -$50,877) and 0.84 (95% CrI: 0.46, 1.40) quality-adjusted life years (QALYs) gained. Conclusions: It is cost-effective to improve indoor ventilation in small businesses in older buildings that lack HVAC systems during the pandemic.